http://hdl.handle.net/11320/8639 2026-06-10T08:25:34Z http://hdl.handle.net/11320/19912 Tytu&#322;: Acid-base properties of hydroxyquinolines in aqueous solution: Effect of hydroxyl group position on thermodynamic protonation parameters Autorzy: Baryłka, Anna; Santonoceta, Giuseppina D.G.; Gattuso, Giuseppe; Godlewska-Żyłkiewicz, Beata; Sgarlata, Carmelo; Milea, Demetrio; Gama, Sofia Abstrakt: The acid-base properties of 2-hydroxyquinoline (2-HQ), 4-hydroxyquinoline (4-HQ), 6-hydroxyquinoline (6-HQ), and 8-hydroxyquinoline (8-HQ) were investigated in this work by UV–Vis spectrophotometry, ISE-H+ potentiometry (glass electrode) and Isothermal Titration Calorimetry (ITC) in KCl(aq) at I = 0.2 mol⋅dm-3, and T = 298.15 K. Potentiometric titrations were also performed at different temperatures (288.15 ≤ T/K ≤ 318.15) to derive, together with direct ITC measurements, the corresponding protonation enthalpy and entropy changes. The analysis of the results obtained using various techniques allowed for a comprehensive characterization of the thermodynamic profile and chemical speciation of the studied hydroxyquinolines. Most importantly, it enabled the evaluation of how the position of the hydroxyl group influences the stability and driving forces involved in the protonation/deprotonation processes of both the quinolinic nitrogen and the hydroxyl groups on the pyridine or benzene ring of the hydroxyquinolines. 2025-01-01T00:00:00Z http://hdl.handle.net/11320/19744 Tytu&#322;: Chemical Speciation and Coordination Behavior of 8‑Hydroxyquinoline-2-carboxylic Acid with Divalent Cations in Aqueous Solution: An Irving-Williams Series Study Autorzy: Baryłka, Anna; Bukrym, Rafał; Ryza, Izabela; Bretti, Clemente; Sinha, Sourab; Cappai, Rosita; Lando, Gabriele; Akintola, Oluseun; Plass, Winfried; Godlewska-Żyłkiewicz, Beata; Brancato, Giuseppe; Milea, Demetrio; Gama, Sofia Abstrakt: In this work, the coordination properties of 8-hydroxyquinoline-2-carboxylic acid (8-HQA, LH₂) toward Mn²⁺, Fe²⁺, Co²⁺, Ni²⁺, Cu²⁺, and Zn²⁺ are discussed. Stability constants for Mn²⁺, Co²⁺, and Ni²⁺/8-HQA systems were determined by ISE-H⁺ (glass electrode) potentiometry, and those of Cu²⁺ and Zn²⁺/8-HQA by ultraviolet−visible (UV−vis) spectrophotometry, in KCl(ₐq) at I = 0.2 mol dm⁻³ and T = 298.2 K. For all systems, three species are formed: MLH⁺, ML, and ML₂²⁻. 8-HQA proved a good sequestering agent of M²⁺ over a wide pH range, as also shown by the calculated pL₀,₅ values. The stability of the formed metal complexes follows the expected Irving−Williams trend, especially concerning the ML₂²⁻ species, with log β₁₂₀: 12.45 ± 0.01 (Mn²⁺) < 13.45 (Fe²⁺) < 15.90 ± 0.04 (Co²⁺) < 17.17 ± 0.05 (Ni²⁺) < 20.64 ± 0.03 (Cu²⁺) > 18.78 ± 0.02 (Zn²⁺). This trend is inversely correlated to the M−N bond length determined by quantum mechanical calculations. These studies, together with voltammetry and electron paramagnetic resonance spectroscopy, allowed us to derive information about the coordination modes, structure, and nature of the formed species. Results support the formation of ML₂²⁻ complexes over possible ML(OH) ⁻, with 8-HQA acting as tridentate in all formed species, including the protonated MLH⁺. 2025-01-01T00:00:00Z http://hdl.handle.net/11320/19743 Tytu&#322;: The accurate assessment of the chemical speciation of complex systems through multi-technique approaches Autorzy: Baryłka, Anna; Godlewska-Żyłkiewicz, Beata; Milea, Demetrio; Gama, Sofia Abstrakt: Chemical speciation studies, i.e., the study of the distribution of an element or compound among its various species in a system of interest, are of fundamental importance. Chemical speciation investigations can be performed mainly by either the direct measurement of the chemical species by different analytical techniques, or by chemical modelling through equilibrium thermodynamic data, based on the use of stability constants (and other thermodynamic parameters) of the formed species. For these purposes, a series of techniques can be used. As soon as the complexity of the systems of interest increases, the need for more detailed information arises. As such, a multi-technique approach is essential to derive complementary data to define a chemical system. In this tutorial review we analysed the most common instrumental techniques employed for chemical speciation studies and equilibrium data analysis. The main advantages and disadvantages of potentiometry, voltammetry, coulometry, UV-Vis spectrophotometry, spectrofluorimetry, NMR, EPR, ITC, HRMS and quantum mechanical calculations, together with brief mention to other less common techniques, are discussed together with a series of practical examples of their application. The main aim of this tutorial review is to provide a practical guide to all scientists interested in the field. 2024-01-01T00:00:00Z http://hdl.handle.net/11320/19742 Tytu&#322;: Chemical speciation of caffeic and p-coumaric acids with selected lanthanides Autorzy: Nalewajko-Sieliwoniuk, Edyta; Gama, Sofia; Arciszewska, Żaneta; Bogdan, Paulina; Naumowicz, Monika; Kalinowska, Monika; Świderski, Grzegorz; Świsłocka, Renata; Lewandowski, Włodzimierz; Lando, Gabriele; Milea, Demetrio; Godlewska-Żyłkiewicz, Beata Abstrakt: Caffeic (CFA) and p-coumaric (p-CA) acids are biologically active compounds commonly found in plants and food of plant origin. Metal complexes of these acids exhibit diverse bioactivity, sometimes even higher than the free ligands. Lanthanide (Ln) complexes with organic ligands also attract the attention of researchers, due to their potential application as novel potential biologically active agents. The aim of the present study was the evaluation of the interactions of CFA and p-CA with representative lanthanides (Ln³⁺ = Eu³⁺, Gd³⁺, and Dy³⁺) in aqueous solution. Potentiometric, spectrophotometric, and 1H NMR techniques were used to study the acid-base behavior of CFA and p-CA, as well as their complexing ability towards Ln³⁺ cations, over a wide range of pH values (2 ≤ pH ≤ 8), in KCl(aq) at I = 0.2 mol dm⁻³ and T = 298.15 ± 0.1 K. The evaluation of the sequestering ability of both ligands towards the studied lanthanides, by means of pM and pL0.5 parameters, show that CFA is a better chelating agent. Opis: Supplementary data to this article can be found online at https://doi.org/10.1016/j.molliq.2023.121915. 2023-05-02T00:00:00Z